Electromagnetic relay with shading ring



Aug. 17, 1965 R. B. STEWART, JR 3,201,660

I ELECTROMAGNETIC RELAY WITH SHADING RING Filed Jan. 18, 1963 INVENTOR Roy B.Stewort,Jr.

BY W ar A ORNEYS United States Patent 3,201,660 ELECTRGMAG'NETIC RELAY WITH SHADING RING Roy B. Stewart, Jr., Princeton, Ind., assignor to American lgdachine & Foundry Company, a corporation of New ersey Filed Jan. 18, 1963, Ser. No. 252,444 6 Claims. (Cl. 317184) This invention relates to electromagnetic relays and, more particularly, to such relays embodying an AC. operated actuating electromagnet.

Considerable difliculty has heretofore been encountered in constructing relatively small relays which, because intended for A.C. operation, employ an actuating electromagnet having a laminated core. In such devices, the core frequently is quite small, a length on the order of /2 inch being typical, and must be fabricated from a number of thin laminations in such fashion that, in the finished core, the laminations are held rigidly against the effects of vibration and are not shorted one to another. Considering a core made up of thin laminations on the order of /2 inch long and approximately inch in width, the use of rivets to secure the laminations together, or of screws or the like to secure the core to the supporting frame of the relay, is highly undesirable because of the attendant loss of core material and the danger of shorting of the laminations.

A general object of the invention is to provide an improved small size relay of the type described.

Another object is to provide such a relay wherein the laminations of the core are assembled without the use of rivets, screws or like fasteners.

A further object is to devise an AC. relay in which the core laminations are afiixed at one end to the relay frame, and are clamped together at their other ends by the shading ring, the coil of the electromagnet being fixed in compression between the shading ring and the relay frame, the main bodies of the laminations all extending in continuous, unbroken fashion between the shading ring and the supporting frame.

Yet another object is to devise a relay of the type described which is unusually simple, involve a minimum number of parts and can be manufactured at low cost.

In order that the manner in which these and other objects are attained in accordance with the invention can be understood in detail, reference is had to the accompanying drawings, which form a part of this specification, and wherein:

FIG. 1 is a side elevational view of a relay constructed in accordance with one embodiment of the invention;

FIG. 2 is an enlarged fragmentary view of a portion of the relay of FIG. 1, showing the core laminations fixed to the supporting frame;

FIG. 3 is a view similar to FIG. 2, showing the shading coil mounted on the core, the bobbin-supported coil being shown in broken lines in its mounted position; and

FEG. 4 is a sectional view take on line 44, FIG. 1.

Referring now to the drawings in detail, it will be seen that the invention is illustrated as applied to a small relay of the general configuration disclosed in US. Patent 3,051,804, issued August 28, 1962, to Mayer. The relay comprises a frame, designated generally at 1, an actuating electromagnet 2, an armature and movable contact assembly 3, and a terminal and fixed contact board 4.

Frame 1 is made from flat metal stock of good magnetic properties and comprises a flat base portion 5, a longer leg portion 6 and a shorter leg portion 7, portions 6 and 7 extending at right angles to the base portion of the frame. Base portion is provided with a rectangular opening 8.

At its free end, leg 6 of the frame presents a pivotal bearing edge against which is disposed the flat main body portion 9 of armature 10, the armature extending beyond the outer face of leg 6 and being provided with dependent stop tails 11 extending along beside leg 6. The armature is retained in pivotal engagement with the bearing edge presented by leg 6 by means of a bracket indicated generally at 12. Bracket 12 is of nonmagnetic sheet metal and has a portion underlying the free ends of stop tails. 11, so that the stop tails cannot directly engage the frame. Bracket 12 also includes a tongue 13 extending through an opening in the armature and bent over to retain the armature in place. A biasing spring 14 of the tension type has one end hooked to the armature on the outer side of leg 6, the other end or" the spring being hooked to a suitable lug presented by bracket 12.

On the side of the main body portion of the armature opposite base portion 5 of the frame, the armature carries a plurality of spring contact arms 15 insulated and fixed in place by insulating blocks 16. At their free ends, spring arms 15 carry the movable contact buttons 17, the arms and contact buttons being so disposed that each contact button 17 is located between two fixed contacts 18 mounted on board 4. It will be noted that the arrangement of biasing spring 14 is such that it pivots the assembly 3 to bring movable contact buttons 17 into normal engagement with selected ones of the fixed contacts 18.

The actuating electromagnet comprises a core made up of a plurality of identical, thin, fiat laminations 19 each having a rectangular main body portion 20, a first end portion 21 of markedly smaller width than the main body portions, and a second end portion 22. The laminations 19 are advantageously all adhered together in face-to-face relation, as by a suitable epoxy resin cement. In this embodiment, there are enough laininations so that the assembled core, as seen in FIG. 4, is of substantially square transverse cross section.

The opening 8 in base portion 5 of the frame is in the form of a rectangle disposed with its long dimension parallel to the plane of frame leg 6 and, therefore, parallel to the pivotal axis of the armature 10. End portions 21 of the laminations are identical and have a width equal to the short dimension of opening 8, the size of opening 8 being such that, when all of the laminations 19 are assembled as seen in FIG. 4 and the smaller ends 21 thereof are inserted through opening 8, the end portions 21 completely fill opening 8.

End portions 21 of the laminations are centered on the longitudinal center lines of the laminations, as will be clear from FIG. 2, and join the main body portions 20 of the laminations at shoulders 23, the shoulders 23 for all of the laminations lying in a common plane extending at right angles to the longitudinal axis of the assembled core. With the core assembled as shown, insertion of small end portions 21 of the laminations through opening 8 seats shoulders 23 flush against the flat face of frame base portion 5 which, in the completed relay, is directed toward the armature. End portions 21 of the laminations are longer than base portion 5 of the frame is thick. Hence, with shoulder 23 engaged with base portion 5, end portions 21 project beyond the base portion of the frame. The assembled core is rigidly fixed to base portion 5 by deforming the tips of all of the end portions 21 to force the end portions 21 into engagement with the walls of opening 8. Thus, a tool having a tapered tip can be used to form a groove 24 extending across the tips of all of the end portions 21, formation of groove 24 splitting the tips of portions 21 to project outwardly, as seen at 25 in FIGS. 2 and 3, over that face of base portion 5 which,

in the completed relay, is directed away from the armature. Alternatively, an X shaped tool can be used to form an X shaped groove (not shown) rather than groove 24. I

End portions 22 of the laminations 19 are each provided with a notch 26 having a flat bottom wall 27 and side walls 28 which diverge at a small angle, each side wall 28 terminating in a small protuberance 29 projecting inwardly, toward the opposite side of the notch.

he winding of the electromagnet 2 is carried by an insulating bobbin 3%, of polypropylene or other suitable material. Bobbin 3d has a tubular body 31 which, as will be clear from FIG. 4, is provided with a bore of substantially square transverse cross section. Body 31 is provided with an annular outwardly projecting end flange 32 at each end of the bobbin. End flanges 32 extend at right angles to the bore of body 31 and are spaced apart by such a distance that, when the bobbin is placed over the assembled core of the electromagnet, with one of the end flanges 32 engaging base portion of the frame, the outer face of the other end flange 32 is disposed slightly above bottom wall 27 of notch 25. Thus, the spacing between bottom wall 27 and shoulders 23 is slightly less than the space between the outer faces of end flanges 32, when the bobbin 30 is in its normal or relaxed condition. The walls of the bore of body portion 31 of the bobbin snugly embrace the lateral surfaces of the assembled core, as will be clear from FIG. 4.

The relay also comprises a shading ring 33 of copper or the like. Ring 33 is formed from a flat sheet of metal, being rectangular in plan, as seen in FIG. 4, and has longer portions 34 and 35 which are both of rectangular transverse cross section. Portion 34 is of square transverse cross section, each side thereof being substantially equal to the length of the bottom walls 27 of notches 26 and also substantially equal to the space between bottom wall 27 and each of the protuberances 29. The notches 26 are identically positioned on all of the laminations 1? and cooperate to form a groove across the end of the core, this groove extending parallel to the pivotal axis of the armature. With the laminations assembled into the com-v pleted core as indicated in FIG. 4, the length of the groove provided by notches 26 is equal to the length of portion 34 of shading ring 33.

With the laminations assembled and secured to base portion 5 of the frame, and with bobbin 3% in position as seen in FIG. 2, the shading ring 33 is applied by forcing portion 34 thereof to seat in the groove afforded by the notches 26, this action compressing the bobbin axially between the shading ring and base portion 5 of the frame. With the shading ring so positioned, the portion 34 of the ring can be upset into engagement with side walls 28 of notches 2%, thereby securing the shading ring to the core. Such distortion of the shading ring expands the ring so that protuberances 29 engage over the face of shading ring portion 34 which, when the relay is assembled, is directed toward the armature. A single tool having a tapered tip can be used to form a groove in the face of the shading ring adjacent protuberances 29 to upset the ring. Distortion of the shading ring in this fashion causes the portion 34 to expand into tight engagement with laminations 14 so that the shading ring is fixed in place against both pivotal movement and movement axially of the core. So fixed in place, the shading ring holds bobbin 30 in compression, it being understood that the insulating material from which the bobbin is made is characterized by a limited degree of yieldability.

As will be clear from FIG. 3, the main body portions 20 of the laminations 19 extend as simple rectangles continuously and unbroken over the entire distance between the shading ring 33 and base portion 5 of the frame. Since the laminations are fixed to the frame by a staking procedure affecting only the smaller end portions 21 which project through opening 8, and since the only other mechanical fastening means applied to the laminations is the 4 shading ring, it is unnecessary to have openings of any sort in the main body portions of the laminations.

The groove afforded by notches 26 is disposed closer to the side of the core which is adjacent frame leg 6 than to the opposite side of the core, so that, as seen in FIG. 4, the groove divides the end face of the core into two rectangular portions of unequal area, the smaller rectangular portion being the one located nearest the pivotal axis of the armature. In practice, the smaller rectangular portion is approximately 40% of the area of the core exposed to the armature, the other rectangular portion being approximately 60% of this area. The distance between the frame base 5 and the exposed end face of the core is made equal to or slightly less than the distance between the frame base and the pivotal bearing edge, presented by leg 6 of the frame, which is engaged by the armature. When the electromagnet 2 is energized, the armature is attracted into direct engagement with the exposed end face of the core, so that the movable contact arms 15 are swung to bring contact buttons 17 into engagement with the fixed contacts which are lowermost, as viewed in P16. 1.

Laminations 19 can be fabricated, as by stamping, from any suitable thin sheet metal stock characterized by high permeability and low magnetic retentivity. Typically, the laminations can be formed from silicon steel sheet on the order of 0.019 inch in thickness, such material having the desired magnetic characteristics and also being susceptible to deformation to allow staking of the assembled core to the frame.

While a particularly advantageous embodiment of the invention has been shown and described, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope f the invention as defined in the appended claims.

What is claimed is:

1. In an electromagnetic relay of the type described, the combination of a magnetic frame having a flat base portion having a rectangular opening;

an electromagnet comprising a core, a bobbin through which said core extends, and a coil wound on said bobbin,

said core comprising a plurality of thin flat laminations each having a rectangular main body portion and an end portion projecting through said opening in said base,

said bobbin comprising a tubular body having a bore of rectangular cross section larger than said opening in the base portion of said frame, and a pair of flat parallel annular end flanges, one of said end flanges being adjacent said base portion of said frame,

said laminations extending through said bobbin body and the other end portions of said laminations projecting beyond the other end flange of said bobbin,

said core being embraced by said bobbin body and completely filling the bore thereof,

said other end portions of said laminations each having a notch opening endwise of the core, said notches being aligned to provide a groove extending transversely across the end of said core opposite said base portion of said frame; and

a flat shading ring overlying said other end flange of said bobbin,

said shading ring having a portion extending through said groove;

said first-mentioned end portions of said laminations being deformed into fixed engagement with said base portion of said frame member,

said portion of said shading ring extending through said groove being deformed into fixed clamping engagement with said other end portions of said lamina tions,

said bobbin being clamped in compression between said shading ring and said base portion of said frame,

said main body portions of said laminations each extending from said shading ring to said base portion of said frame in continuous unbroken fashion.

2. A relay in accordance with claim 1 and wherein said main body portions of said laminations are adhesively secured to each other.

3. A relay in accordance with claim 1 and wherein said groove divides the end portion of said core opposite said base portion of said frame member into two rectangular portions, and

said shading ring extends rectangularly and directly embraces one of said rectangular portions.

4. In an electromagnetic relay of the type described,

the combination of a magnetic frame comprising a flat base portion having a rectangular opening,

and

a leg projecting at right angles from said base portion;

a magnetic armature mounted on said leg for pivotal movement about an axis parallel to one of the sides of said rectangular opening,

said armature having a flat face directed toward said base portion of said frame;

an electromagnet comprising a core, a bobbin through which said core extends, and a coil Wound on said bobbin,

said core comprising a plurality of thin fiat laminations each having a rectangular main body portion, a first end portion of smaller width than the main body portion, and a second end portion provided with a notch opening endwise of the lamination,

said laminations being assembled face-to-face with said notches aligned to form a groove extending across the corresponding end face of the core, said first end portions of said laminations projecting through said rectangular opening in said base portion and being deformed into fixed engagement with said base portion to fixedly secure the core to said frame,

the core projecting from said base portion parallel to and beside said frame leg with the grooved end face thereof directed toward said fiat face of said armature, said bobbin comprising a tubular body having a bore of rectangular cross section larger than said opening in said base portion, and a pair of flat parallel annular end flanges, the core extending through said bobbin body with said second end portions of said laminations projecting away from the bobbin, one of said end flanges being adjacent said base portion and the other adjacent said notches, said bobbin body embracing the core with said laminations completely filling the bore of said body; and a flat shading ring extending through the groove formed by said notches and overlying said other end flange of said bobbin,

said shading ring being deformed to be clamped between the sides of said notches and fix the shading ring rigidly to said core, said bobbin being clamped in compression between said shading ring and said base portion of the frame, said main body portions of said laminations each extending from said shading ring to said base portion in continuous unbroken fashion, said notches dividing said end face of the core into two rectangular portions each extending parallel to the pivotal axis of said armature. 5. A relay in accordance with claim 4 and wherein said two rectangular portions of said end face are elongated in a direction parallel to said pivotal axis, and the one of said portions nearer said pivotal axis being narrower than the other of said portions. 6. A relay in accordance with claim 4 and wherein the sides of said notches each terminate, at the mouth of the notch, in a protuberance projecting over said deformed shading ring.

References Cited by the Examiner UNITED STATES PATENTS 3/42 Seeley 200-87 8/62 Mayer 20 )87 

1. IN AN ELECTROMAGNETIC RELAY OF THE TYPE DESCRIBED, THE COMBINATION OF A MAGNETIC FRAME HAVING A FLAT BASE PORTION HAVING A RECTANGULAR OPENING; AN ELECTROMAGNET COMPRISING A CORE, A BOBBIN THROUGH WHICH SAID CORE EXTENDS, AND A COIL WOUND ON SAID BOBBIN, SAID CORE COMPRISING A PLURALITY OF THIN FLAT LAMINATIONS EACH HAVING A RECTANGULAR MAIN BODY PORTION AND AN END PORTION PROJECTING THROUGH SAID OPENING IN SAID BASE, SAID BOBBIN COMPRISING A TUBULAR BODY HAVING A BORE OF RECTANGULAR CROSS SECTION LARGER THAN SAID OPENING IN THE BASE PORTION OF SAID FRAME, AND A PAIR OF FLAT PARALLEL ANNULAR END FLANGES, ONE OF SAID END FLANGES BEING ADJACENT SAID BASE PORTION OF SAID FRAME, SAID LAMINATIONS EXTENDING THROUGH SAID BOBBIN BODY AND THE OTHER END PORTIONS OF SAID LAMINATIONS PROJECTING BEYOND THE OTHER END FLANGE OF SAID BOBBIN, SAID CORE BEING EMBRACED BY BOBBIN BODY AND COMPLETELY FILLING THE BORE THEREOF, SAID OTHER END PORTIONS OF SAID LAMINATIONS EACH HAVING A NOTCH OPENING ENDWISE OF THE CORE, SAID NOTCHES BEING ALIGNED TO PROVIDE A GROOVE EXTENDING TRANSVERSELY ACROSS THE END OF SAID CORE OPPOSITE SAID BASE PORTION OF SAID FRAME; AND A FLAT SHADING RING OVERLYING SAID OTHER END FLANGE OF SAID BOBBIN, SAID SHADING RING HAVING A PORTION EXTENDING THROUGH SAID GROOVE; SAID FIRST-MENTIONED END PORTIONS OF SAID LAMINATIONS BEING DEFORMED INTO FIXED ENGAGEMENT WITH SAID BASE PORTION OF SAID FRAME MEMBER, SAID PORTION OF SAID SHADING RING EXTENDING THROUGH SAID GROOVE BEING DEFORMED INTO FIXED CLAMPING ENGAGEMENTT WITH SAID OTHER END PORTIONS OF SAID LAMINATIONS, SAID BOBBIN BEING CLAMPED IN COMPRESSION BETWEEN SAID SHADING RING AND SAID BASE PORTION OF SAID FRAME, SAID MAIN BODY PORTIONS OF SAID LAMINATIONS EACH EXTENDING FROM SAID SHADING RING TO SAID BASE PORTION OF SAID FRAME IN CONTINUOUS UNBROKEN FASHION. 